import java.util.List;

public class MyLinkedList {
    static class ListNode {
        public int val;
        public ListNode prev;
        public ListNode next;

        public ListNode(int val) {
            this.val = val;
        }
    }

    private ListNode head;
    private ListNode last;



    public void addFirst(int data) {
        ListNode node = new ListNode(data);

         if(head == null) {
            head = node;
            last = node;
            return;
         }

         node.next = head;
         head.prev = node;
         head = node;
    }


    public void addLast(int data) {
        ListNode node = new ListNode(data);

        if(head == null) {
            head = node;
            last = node;
        }else {
            last.next = node;
            node.prev = last;
            last = node;
        }

    }


    public void addIndex(int index,int data) {
        if(index < 0 || index > size()) {
            throw new IndexOutOfBounds("双向链表index不合法");
        }

        if(index == 0) {
            addFirst(data);
            return;
        }
        if(index == size()) {
            addLast(data);
            return;
        }

        ListNode cur = head;
        while(index != 0) {
            cur = cur.next;
            index--;
        }

        ListNode node = new ListNode(data);
        node.next = cur;
        cur.prev.next = node;
        node.prev = cur.prev;
        cur.prev = node;
    }

    public void remove(int key) {
        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {

                if(cur == head) {
                   head = head.next;
                   if(head != null) {
                       head.prev = null;
                   }
                }
                else {
                    cur.prev.next = cur.next;

                    if(cur.next != null) {
                        cur.next.prev = cur.prev;
                    }
                    else {
                        last = last.prev;
                    }
                }
                return;
            }
            else {
                cur = cur.next;
            }
        }
    }


    public void removeAll(int key) {
        ListNode cur = head;
        while(cur != null) {
            if(cur.val == key) {

                if(cur == head) {
                    head = head.next;
                    if(head != null) {
                        head.prev = null;
                    }
                    else {
                        last = null;
                    }
                }
                else {
                    cur.prev.next = cur.next;

                    if (cur.next != null) {
                        cur.next.prev = cur.prev;
                    } else {
                        last = last.prev;
                    }
                }
            }
//            else {
//                cur = cur.next;
//            }
            cur = cur.next;
        }
    }

    //得到单链表的长度
    public int size() {
        int count = 0;
        ListNode cur = head;
        while (cur != null) {
            count++;
            cur = cur.next;
        }
        return count;
    }

    public void display() {
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val + " ");
            cur = cur.next;
        }
        System.out.println();
    }

    //查找是否包含关键字key是否在单链表当中
    public boolean contains(int key) {
        ListNode cur = head;
        while (cur != null) {
            if (cur.val == key) {

                return true;
            }
            cur = cur.next;

        }
        return false;
    }

    public void clear() {
       ListNode cur = head;

       while(cur != null) {
           ListNode curNext = cur.next;
           cur.prev = null;
           cur.next = null;
           cur = curNext;
       }
       head = null;
       last = null;
    }
}